Magnetic resonance imaging apparatuses irradiate high-frequency magnetic pulses in the condition that an object to be examined is placed in a homogeneous magnetic field to excite atomic nuclei such as hydrogen in the living body, and measure nuclear magnetic resonance signals (NMR signals) produced by the excitation. Then the measurement regions in the living body are to be imaged and displayed based on the magnetic resonance information such as the density distribution of the measured signals or distribution of relaxation time thereof, to be used for purposes such as medical diagnosis.
Such MRI apparatuses can obtain a T1 weighted image by reflecting the difference of longitudinal relaxation time of the atomic nucleus spin in the respective tissues (T1) to the contrast of the image. As for the method for imaging T1 weighted images, for example, there is the IR method for contrastively reflecting longitudinal magnetic intensity of the respective tissues to the image in the TI elapsed time by first applying IR pulses, acquiring echo signals by a method such as the spin echo method or gradient echo method after the passage of a predetermined inversion time (TI) and reconstructing a real component image.
The usual magnetic resonance imaging method reconstructs and displays absolute value images wherein the real component and imaginary component are made into an absolute value after the echo signal is performed with quadrature detection.
However, in the case of imaging and reconstructing by adding IR pulses in the above-described IR method, there is a difficulty in acquiring accurate T1 contrast attributed to the folding generated in the signal intensity of longitudinal magnetization having a negative value upon TI time passage. Due to this, the method is often used for acquiring accurate T1 contrast by preventing the generation of folding of signal intensity through reconstructing images using only real components and maintaining a sign of longitudinal magnetization of the respective tissues in a predetermined TI.
In Patent Document 1, upon performing image reconstruction using only real component in the IR method, the phase data to be the reference is obtained by performing template scan by setting the phase encode as zero without applying IR pulses before the imaging scan for acquiring the echo signals for image reconstruction. And the method is disclosed therein for obtaining an image wherein positive and negative polar characters are correct by correcting the signals acquired in the measurement for image acquisition using the reference phase data. By such method, it is possible to obtain a T1 weighted image which accurately reflects T1 contrast.    Patent Document 1: Japanese Patent No. 3576069